Calculating Energy Consumption of Motor Systems with Varying Load using Iso Efficiency Contours

摘要

Increasing awareness of ecological problemsforces machine manufacturers to design greener machines. Thisimplies amongst other things the selection of the most efficientelectric motor system for their specific application. On theother hand, machine building applications evolve more andmore from constant speed and load characteristics to varyingspeed and load applications. Therefore, the motor system thatis used evolves more and more from direct online (DOL) tomotors fed by a variable speed drive (VSD). However, currentefficiency standardization focuses on DOL applications, andcan by consequence not offer assistance to the machine builderto select the most efficient motor-VSD combination for hisparticular varying load application. The goal of this paper is topresent a methodology that allows to predict the energyconsumption for a specific motor-VSD combination and aspecific varying speed-load application, using the fairly newconcept of iso efficiency contours. By comparing the predictedenergy consumption for a number of selected combinations, themost efficient one is revealed.